Computer system and control method for controlling processor execution of a prefetech command

A processor reads a program including a prefetch command and a load command and data from a main memory, and executes the program. The processor includes: a processor core that executes the program; a L2 cache that stores data on the main memory for each predetermined unit of data storage; and a prefetch unit that pre-reads the data into the L2 cache from the main memory on the basis of a request for prefetch from the processor core. The prefetch unit includes: a L2 cache management table including an area in which a storage state is held for each position in the unit of data storage of the L2 cache and an area in which a request for prefetch is reserved; and a prefetch control unit that instructs, the L2 cache to perform the request for prefetch reserved or the request for prefetch from the processor core.